1. Field of the Invention
The present invention relates to a substrate mounted thereon with a heat-generating electronic element such as an IC, and also to a liquid ejection head including the substrate.
2. Description of Related Art
An electronic device such as a portable phone, a personal computer, or the like includes many electronic elements such as an integrated circuit (IC), a resistance, a capacitor, etc. which are mounted on a substrate. When a heat-generating electronic element such as an IC is mounted, heat generated by the electronic element must surely be radiated to the outside in order to prevent damage to the electronic element itself and damage to other elements therearound. However, for the purpose of downsizing an electronic device, there is a growing tendency for many electronic elements to be disposed close to each other in a small region on the substrate. This makes it difficult to radiate heat generated by the electronic elements to the outside. Therefore proposed are various electronic devices capable of efficient radiation of heat generated by an electronic element.
For example, Japanese Patent Unexamined Publication No. 2003-76445 discloses an electronic device including a heat conductor, cooling fan, and a heat exchanger. The heat conductor is made of a metallic plate, etc. which is in contact with a surface of a heat-generating electronic element such as a CPU. The cooling fan is disposed near the heat conductor. The heat exchanger transmits to a heat medium heat which has come to the heat conductor. Heat is transmitted from the electronic element to the heat conductor, and then the heat exchanger transmits the heat to the heat medium via which the heat is radiated to the outside.